How to find coefficients of a polynomial using Matlab?

Hi, how can I write the code for the following question: Given the cubic polynomial p(x)=c1+c2x+c3x^2+c4x^3 with a prescribed behaviour:p(x k)=y k, for k=1,2,3,4 In addition; 1) n is an integer parameter. 2) a matrix M will be generated by the value of the parameter n. The matrix M will have size 2×4. The entries of M are given by M(1,k)=x k and M(2,k)=y k for k=1,2,3,4.

How could I use Matlab to Create 4×1 column vector v=[c1,c2,c3,c4] (where c1,c2,c3 and c4 are the coefficients of the polynomial p(x))?

Thanks!

[Are Mjaavatten]

I believe that polyfit ia what you are looking for. See also polyval.

Answer 1

[Ameer Hamza]

For a given matrix M you can use the following command to find coefficients vector v.

v = polyfit(M(1,:), M(2,:));

This will return coefficients as v = [c4 c3 c2 c1]. You can reverse the coefficient vector as

v = fliplr(v);

to get vector is the required order.

Answer 2

[AMIR AZMI ABD RAHMAN]

hi cheri can i see ur programs